Self-assembly of a phospholipid Langmuir monolayer using coarse-grained molecular dynamics simulations

Molecular dynamics simulations using a coarse-grained (CG) model for dimyristoyl-phosphatidyl-choline and water molecules have been carried out to follow the self-assembly process of a Langmuir monolayer. We expand on a previous study of the characteristics of the CG model where we compare the rotational and translational constants of the present model to those of an all-atom (AA) model, and find that the rotational and translational timescales are up to two orders of magnitude faster than in an AA model. We then apply the model to the self-assembly of a Langmuir monolayer. The initial randomly distributed system, which consists of 80 lipids and 5000 water sites, quickly self-assembles into two Langmuir monolayers and a micelle in the bulk water region. The micelle slowly diffuses towards and fuses with one of the interfacial monolayers, leaving the final equilibrated state with a Langmuir monolayer at each of the two air/water interfaces. The effective speed-up gained from the CG approach gives access to timescales and spatial scales that are much larger than those currently accessible with AA models.